In order to test our hypothesis that the coenzyme specificity of L- fucose dehydrogenase determines whether or not L-fucose will be catabolized by a given species or the intact L-fucose eliminated in the urine, we shall study the conversion of (C14)-L-fucose to 14CO2 in selected animal species, using both intact specimens and organ slices. We will use the same technique to test the metabolic significance of an observed 18% elevation of L-fucose dehydrogenase in livers of diabetic rats as compared to normal controls. We have recently reported that the activities of 4 glycosidases of lysosomal origin are elevated in epididymal fat pads and serum of diabetic rats compared to normal controls (in press). The activities were measured with PNP-substrates. The enzymes catalyzing this hydrolysis are not necessarily the same enzymes which catalyze hydrolysis of saccharide-components of glycoproteins and glycolipids. We shall, therefore, test serum enzymes for activity with glycoprotein and glycolipids, assaying by means of GLC-chromatography. We will attempt to identify the organ of origin of the glycosidases elevated in diabetic sera by means of gel electrophoresis, isoelectric focusing, and other appropriate techniques.